Compressor

ABSTRACT

A reed valve for opening and closing a discharge port of a compressor mechanism is provided with a protruding part which is formed at a distal end thereof to come in and out of the discharge port. The shape of the discharge port and the shape of the reed valve are determined such that flow passage areas S 0 , S 1  and S 2  at different parts of the discharge port satisfy S 2≧ S 1≧ S 0  when the reed valve is lifted to a maximum level. Accordingly, a refrigerant is discharged through the discharge port without reducing the amount of flow of the refrigerant, thereby reducing loss of pressure.

TECHNICAL FIELD

The present invention relates to a compressor. In particular, it relatesto measures against a loss of discharge pressure.

BACKGROUND ART

So far, compressors have been used in air conditioners and the like tocompress a refrigerant in a refrigerant circuit. A known example of suchcompressors is a rotary compressor including a compressor mechanism anda motor for driving the compressor mechanism in a hermetic casing.

When the motor is driven, a piston revolves in a cylinder chamber of thecompressor mechanism. According to the revolutions, a low pressurerefrigerant is sucked into a suction chamber through a suction pipe,compressed to raise its pressure in a compressor chamber, and thendischarged out to space in the casing through a discharge port.

The discharge port is generally provided with a flat reed valve. Whenthe pressure in the compressor chamber exceeds a certain value, a distalend of the reed valve is warped to open the discharge port. After therefrigerant is discharged out of the compressor chamber to the space inthe casing, the reed valve closes the discharge port by spring force ofits own.

In the compressor mechanism as described above, however, reexpansion ofthe compressed refrigerant occurs to reduce the efficiency of thecompressor (loss by reexpansion). Specifically, even after the dischargeoperation of the refrigerant, part of the refrigerant still remains inthe volume of the discharge port, i.e., a dead volume. The remainingrefrigerant reexpands in the compressor chamber to reduce volumeefficiency.

To solve the above-described problem, for example, Japanese UnexaminedPatent Publication No. 2001-280254 proposes a compressor provided with areed valve having a protruding part to be fitted in the discharge port,i.e., a so-called poppet valve. According to the compressor, theprotruding part of the reed valve is fitted in the discharge port afterthe discharge is terminated, thereby reducing the dead volume.Therefore, the refrigerant remains less in the dead volume.

Problem to Solve

When the reed valve of the compressor is lifted to the maximum level(full open state), the protruding part of the reed valve may possiblyreduce the area of a flow passage formed in the discharge port. Thereduced flow passage area causes flow resistance, thereby increasing aloss of discharge pressure. Further, when the reed valve is lifted tothe maximum level, the refrigerant flows at high speed and the flowresistance is likely to increase. Thus, the reduction in flow passagearea leads to a problem of increase in loss of discharge pressure.

The present invention has been achieved in view of the above-describedproblem. An object of the present invention is to reduce the loss ofdischarge pressure by forming a flow passage whose area is not reducedat any part of the discharge port at least when the reed valve is liftedto the maximum level to increase the flow rate.

DISCLOSURE OF THE INVENTION

The present invention solves the problem as described below.

Specifically, a compressor according to a first aspect of the presentinvention includes a reed valve (41) which opens and closes a dischargeport (29) of a compressor mechanism (20) and includes a flat part (41 a)and a protruding part (41 b) formed at a distal end of the flat part (41a) to come in and out of the discharge port (29), wherein the shape ofthe discharge port (29) and the shape of the reed valve (41) aredetermined to satisfy S2≧S1≧S0 wherein S0 is an opening area of an inlet(29 a) of the discharge port (29), S1 is the smallest sectional area ofa flow passage formed between the protruding part (41 b) and thedischarge port (29) when the reed valve (41) is lifted to the maximumlevel and S2 is the smallest sectional area of a flow passage formedbetween the flat part (41 a) and the outer periphery of an outlet (29 b)of the discharge port (29) when the reed valve (41) is lifted to themaximum level.

According to the first aspect of the present invention, as shown in FIG.4, the flow passage areas S0, S1 and S2 at different parts of thedischarge port (29) satisfy S2≧S1≧S0 when the reed valve (41) is liftedto the maximum level. Therefore, the flow passage area is not reduced atany part of the discharge port (29). Specifically, the amount of acompressed fluid flow will never be reduced during the period from whenthe fluid enters the discharge port (29) through the inlet (29 a) toflow between the discharge port (29) and the protruding part (41 b)until the fluid passes between the discharge port (29) and the flat part(41 a). Accordingly, flow resistance caused by reduction in flow passagearea is less likely to occur and a loss of discharge pressure isreduced. In particular, as the above-described effect is achieved whenthe reed valve (41) is lifted to the maximum level, i.e., when the fluidflows at high speed and the flow resistance is likely to increase, theloss of discharge pressure is reduced with efficiency.

According to a second aspect of the present invention related to thefirst aspect of the present invention, the discharge port (29) istapered from the outlet (29 b) to the inlet (29 a).

According to the second aspect of the present invention, the flowpassage area S1 of the discharge port (29), i.e., the smallest sectionalarea of a flow passage formed between the discharge port (29) and theprotruding part (41 b), increases with reliability. Accordingly, theflow passage area S1 surely becomes equal to or larger than the openingarea S0 of the inlet (29 a) of the discharge port (29).

According to a third aspect of the present invention related to thefirst or second aspect of the present invention, a seat (22 b) is formedat the outer periphery of the outlet (29 b) of the discharge port (29)such that the seat (22 b) contacts the flat part (41 a).

According to the third aspect of the present invention, the flat plate(41 a) contacts the outer periphery of the outlet (29 b) of thedischarge port (29) to seal the discharge port (29). Accordingly, thereis no need of adjusting the shape of the protruding part (41 b) to theshape of the discharge port (29), though it is required in the casewhere the discharge port (29) is sealed by contact between theprotruding part (41 b) and the inner surface of the discharge port (29).Thus, the protruding part (41 b) is made smaller than the discharge port(29) and the smallest sectional area S1 of the flow passage formedbetween the discharge port (29) and the protruding part (41 b) increaseswith reliability.

Effect

According to the first aspect of the present invention, the shape of thedischarge port (29) and the shape of the reed valve (41) are determinedto satisfy S2≧S1≧S0 wherein S0 is an opening area of an inlet (29 a) ofthe discharge port (29), S1 is the smallest sectional area of a flowpassage formed between the protruding part (41 b) and the discharge port(29) when the reed valve (41) is lifted to the maximum level and S2 isthe smallest sectional area of a flow passage formed between the flatpart (41 a) and the outer periphery of an outlet (29 b) of the dischargeport (29) when the reed valve (41) is lifted to the maximum level.Therefore, the amount of a fluid flow will never be reduced during theperiod from when the fluid enters the discharge port (29) through theinlet (29 a) until the fluid passes between the discharge port (29) andthe flat part (41 a). As the flow passage area is not reduced, flowresistance caused by reduction in flow passage area is prevented fromoccurring. Therefore, even during high speed operation when the fluidflows faster and is likely to receive greater flow resistance, the lossof discharge pressure is reduced with efficiency. As a result, theefficiency of the compressor improves.

According to the second aspect of the present invention, the dischargeport (29) is tapered from the outlet (29 b) to the inlet (29 a).Therefore, the smallest sectional area S1 of the flow passage formedbetween the discharge port (29) and the protruding part (41 b) when thereed valve (41) is lifted to the maximum level increases as comparedwith the case where the discharge port (29) is cylindrical. Thus, thesmallest sectional area S1 is surely made equal to or larger than theflow passage area S0 and the flow resistance caused by reduction in flowpassage area is surely prevented from occurring.

According to the third aspect of the present invention, the seat (22 b)is provided at the outer periphery of the outlet (29 b) of the dischargeport (29). Accordingly, there is no need of adjusting the shape of theprotruding part (41 b) to the shape of the discharge port (29), thoughit is required in the case where the discharge port (29) is sealed bycontact between the protruding part (41 b) and the inner surface of thedischarge port (29). Thus, the protruding part (41 b) is made smallerthan the discharge port (29). Moreover, the flow passage area S1 is madelarger to prevent the occurrence of the flow resistance caused byreduction in flow passage area.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view illustrating a rotary compressor according toan embodiment.

FIG. 2 is a horizontal sectional view illustrating the rotary compressoraccording to the embodiment.

FIG. 3 is an enlarged sectional view illustrating the mechanism of adischarge valve system according to the embodiment.

FIG. 4 is a sectional view illustrating a reed valve of the embodimentwhich is lifted to the maximum level.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a detailed explanation of the embodiment of the presentinvention will be provided with reference to the drawings.

Embodiment of the Invention

A compressor of the present embodiment is a so-called rotary compressor(1) including a rotating piston as shown in FIGS. 1 and 2 (hereinaftersimply referred to as a compressor). The compressor (1) includes acompressor mechanism (20) and a motor (30) for driving the compressormechanism (20) in a dome-shaped hermetic casing (10). The compressor (1)functions as a variable capacity compressor in which the motor (30) iscontrolled by an inverter to vary the capacity of the compressorstepwise or continuously. In the compressor (1), the compressormechanism (20) is driven by the motor (30) to perform suction,compression and discharge of a refrigerant to circulate the refrigerantin a refrigerant circuit.

A suction pipe (14) and a discharge pipe (15) are provided at a lowerpart and an upper part of the casing (10), respectively.

The compressor mechanism (20) includes a cylinder (21), a front head(22), a rear head (23) and a piston (24). The front head (22) and therear head (23) are fixed to the top end and the bottom end of thecylinder (21), respectively.

The cylinder (21) is a thick-walled cylindrical piece. A columnarcylinder chamber (25) is defined by the inner circumference surface ofthe cylinder (21), the bottom surface of the front head (22) and the topsurface of the rear head (23). The cylinder chamber (25) is adapted toallow the piston (24) to revolve therein.

The motor (30) includes a stator (31) and a rotor (32). A drive shaft(33) is connected to the rotor (32). The drive shaft (33) passes throughthe center of the casing (10) and penetrates the cylinder chamber (25)in the vertical direction. The front head (22) and the rear head (23)are provided with bearings (22 a and 23 a) for supporting the driveshaft (33), respectively.

The drive shaft (33) includes a shaft body (33 b) and an eccentric part(33 a) situated in the cylinder chamber (25). The eccentric part (33 a)has a larger diameter than that of the shaft body (33 b) and its centeris misaligned with the rotation center of the drive shaft (33) by acertain amount. The piston (24) of the compressor mechanism (20) isfitted around the eccentric part (33 a). As shown in FIG. 2, the piston(24) is annular and configured such that its outer circumference surfacecontacts the inner circumference surface of the cylinder (21)substantially at a certain point.

The cylinder (21) is provided with a blade slit (21 a) formed along theradius direction of the cylinder (21). A blade (26) in the form of arectangular plate is disposed in the blade slit (21 a) to be slidable inthe radius direction of the cylinder (21). The blade (26) is biasedinward in the radius direction by a spring (27) disposed in the bladeslit (21 a) such that its end is always in contact with the outercircumference surface of the piston (24).

The blade (26) divides the cylinder chamber (25) formed between theinner circumference surface of the cylinder (21) and the outercircumference surface of the piston (24) into a suction chamber (25 a)and a compression chamber (25 b). In the cylinder (21), a suction port(28) is formed to penetrate the cylinder (21) in the radius directionfrom the outer circumference surface to the inner circumference surfacesuch that a suction pipe (14) communicates with the suction chamber (25a). Further, the front head (22) is provided with a discharge port (29)penetrating the front head in the axial direction of the drive shaft(33) to communicate the compression chamber (25 b) with space in thecasing (10).

The front head (22) is provided with a discharge valve system (40) foropening and closing the discharge port (29). The front head (22) isfurther equipped with a muffler (44) covering the top surface thereof.

As shown in FIG. 3, the discharge valve system (40) includes a reedvalve (41) and a valve guard (42). The reed valve (41) is sandwichedbetween the valve guard (42) laid over the reed valve (41) and the fronthead (22). The reed valve (41) and the valve guard (42) are fixed to thefront head (22) at the proximal ends thereof by a fastening bolt (43).

The discharge port (29) includes an inlet (29 a) opened in thecompression chamber (25 b) and an outlet (29 b) opened in the space inthe casing (10). The discharge port (29) is tapered from the outlet (29b) to the inlet (29 a).

The reed valve (41) includes a thin flat part (41 a). Further, aprotruding part (41 b) protruding toward the discharge port (29) isformed at the distal end of the flat part (41 a). Specifically, the reedvalve (41) is a so-called poppet valve. The protruding part (41 b) istapered toward the distal end thereof substantially in the same manneras the discharge port (29). The reed valve (41) is configured such thatthe protruding part (41 b) comes in and out of the discharge port (29)when the reed valve (41) is closed or opened. The outer periphery of theoutlet (29 b) of the discharge port (29) is protruded to function as aseat (22 b) for receiving the flat part (41 a) of the reed valve (41).Specifically, when the pressure in the compression chamber (25 b) israised to a certain level, the flat part (41 a) is warped along thecurvature of the distal end of the valve guard (42) and the protrudingpart (41 b) comes out of the discharge port (29). Thus, the dischargeport (29) is opened to discharge a high pressure gas refrigerant out tothe space in the casing (10). On the other hand, when the pressure inthe compression chamber (25 b) is reduced after the gas refrigerant hasbeen discharged, the protruding part (41 b) comes in the discharge port(29) under the spring force of the reed valve (41) and the flat part (41a) comes into contact with the seat (22 b) to close the discharge port(29). While the discharge port (29) is in a closed state, the protrudingpart (41 b) occupies almost all the volume in the discharge port (29).

As a characteristic feature of the present invention, the shape of thedischarge port (29) and the shape of the reed valve (41) are determinedsuch that flow passage areas S0, S1 and S2 at different parts of thedischarge port (29) satisfy S2≧S1≧S0 when the reed valve (41) is liftedto the maximum level as shown in FIG. 4, i.e., when the protruding part(41 b) moves to the farthest position from the discharge port (29). InFIG. 4, the valve guard (42) and the fastening bolt (43) are omitted.

The flow passage area S0 is an opening area of the inlet (29 a) of thedischarge port (29). The flow passage area S1 is the smallest sectionalarea of a flow passage formed between the discharge port (29) and theprotruding part (41 b). The flow passage area S2 is the smallestsectional area of a flow passage formed between the seat (22 b) which isthe outer periphery of the outlet (29 b) of the discharge port (29) andthe flat part (41 a). That is, the flow passage areas S0 to S2 are thesmallest areas at the inlet, inside and outlet of the discharge port(29), respectively.

The shapes of the discharge port (29) and the reed valve (41) aredetermined such that the flow passage areas S0, S1 and S2 become equalto each other or increase in this order. That is, their shapes aredetermined such that a flow passage formed in the discharge port (29) isnot reduced at any part when the reed valve (41) is lifted to themaximum level. Therefore, when the amount of a fluid flow is maximizedas the reed valve (41) is lifted to the maximum level, the amount of thefluid flowing from the compressor chamber (25 b) will never be reducedduring the period from when the fluid enters the discharge port (29)until the fluid is discharged out to the space in the casing (10).

The discharge port (29) is tapered from the outlet (29 b) to the inlet(29 a). Therefore, the flow passage area S1, i.e., the smallestsectional area of the flow passage formed between the discharge port(29) and the protruding part (41 b) when the reed valve (41) is liftedto the maximum level, increases as compared with the case where thedischarge port (29) is cylindrical. Thus, the flow passage area S1surely becomes equal to or larger than the flow passage area S0.

As the seat (22 b) is provided at the outer periphery of the outlet (29b) of the discharge port (29), there is no need of adjusting the shapeof the protruding part (41 b) to the shape of the discharge port (29),though it is required in the case where the discharge port (29) issealed by contact between the protruding part (41 b) and the innersurface of the discharge port (29). Thus, the protruding part (41 b) ismade smaller than the discharge port (29). By so doing, the smallestsectional area S1 of the flow passage formed between the discharge port(29) and the protruding part (41 b) becomes large.

For example, the shapes of the discharge port (29) and the reed valve(41) are determined by adjusting the diameter øD of the inlet (29 a) ofthe discharge port (29) and the taper angle θ of the discharge port(29). The maximum lift level H of the reed valve (41) may be adjusted asrequired to establish the above-described relationship among the flowpassage areas S0 to S2.

Operation

Hereinafter, an explanation of how the above-described compressor isoperated is provided below.

When the motor (30) is energized, the rotor (32) rotates. The rotationsof the rotor (32) are transferred to the piston (24) of the compressormechanism (20) via the drive shaft (33). In this way, the compressormechanism (20) performs the compression as required.

The compression performed by the compressor mechanism (20) is explainedmore specifically with reference to FIG. 2. When the piston (24) isdriven by the motor (30) to revolve to the right (clockwise), thecapacity of the suction chamber (25 a) increases as the piston revolvesand a low pressure refrigerant is sucked into the suction chamber (25 a)via the suction port (28). The suction of the refrigerant into thesuction chamber (25 a) is continued until the piston (24) revolving inthe cylinder chamber (25) comes to the immediate right of the suctionport (28) to contact the cylinder (21).

When the piston (24) makes a single revolution as described above andthe suction of the refrigerant is terminated, the compression chamber(25 b) for compressing the refrigerant is provided. Next to thecompression chamber (25 b), a new suction chamber (25 a) is formed andthe suction of the refrigerant therein is performed repeatedly. As thepiston (24) revolves, the capacity of the compression chamber (25 b)decreases to compress the refrigerant in the compression chamber (25 b).When the pressure in the compression chamber (25) is raised to a certainlevel, the protruding part (41 b) of the reed valve (41) comes out ofthe discharge port (29) to open the discharge port (29). The refrigerantin the compression chamber (25 b) enters the discharge port (29) throughthe inlet (29 a), flows between the discharge port (29) and theprotruding part (41 b), and then passes between the seat (22 b) and theflat part (41 a) to go out to the space in the casing (10). After thehigh pressure refrigerant is discharged and the pressure in thecompression chamber (25 b) is reduced, the protruding part (41 b) of thereed valve (41) comes in the discharge port (29) by its own rigidity(spring force) and the flat part (41 a) comes into contact with the seat(22 b) to close the discharge port (29). In this way, the suction,compression and discharge of the refrigerant is performed repeatedly.

During high speed operation, the amount of discharged gas increases andthe reed valve (41) is lifted to the maximum level (warped at themaximum). The amount of a refrigerant flow from the compression chamber(25 b) will never be reduced during the period from when the refrigerantenters the discharge port (29) through the inlet (29 a) until therefrigerant passes between the seat (22 b) and the flat plate (41 a).Therefore, even during high speed operation where the refrigerant flowsfaster and is likely to receive greater flow resistance, the flowresistance caused by reduction in flow passage area is prevented fromoccurring. Thus, the loss of discharge pressure is reduced withefficiency.

Effect of the Embodiment

As described above, according to the present embodiment, the shapes ofthe discharge port (29) and the reed valve (41) are determined tosatisfy S2≧S1≧S0, wherein S0 is the opening area of the inlet (29 a) ofthe discharge port (29), S1 is the smallest sectional area of the flowpassage formed between the protruding part (41 b) and the discharge port(29) when the reed valve (41) is lifted to the maximum level and S2 isthe smallest area of the flow passage formed between the flat plate (41a) and the seat (22 b) when the reed valve (41) is lifted to the maximumlevel. Accordingly, the amount of the refrigerant flow from thecompression chamber (25 b) will never be reduced during the period fromwhen the refrigerant enters the discharge port (29) through the inlet(29 a) until the refrigerant passes between the seat (22 b) and the flatplate (41 a). Therefore, even during high speed operation where therefrigerant flows faster and is likely to receive greater flowresistance, the flow resistance caused by reduction in flow passage areais prevented from occurring. Thus, the loss of discharge pressure isreduced with efficiency.

As the discharge port (29) is tapered from the outlet (29 b) to theinlet (29 a), the flow passage area S1, i.e., the smallest sectionalarea of the flow passage formed between the discharge port (29) and theprotruding part (41 b) when the reed valve (41) is lifted to the maximumlevel, increases as compared with the case where the discharge port iscylindrical. Thus, the flow passage area S1 surely becomes equal to orlarger than the flow passage area S0 and the flow resistance caused byreduction in flow passage area is prevented from occurring withreliability.

Further, as the seat (22 b) is provided at the outer periphery of theoutlet (29 b) of the discharge port (29) to contact the flat part (41a), there is no need of adjusting the shape of the protruding part (41b) to the shape of the discharge port (29), though it is required in thecase where the discharge port (29) is sealed by contact between theinner circumference surface of the discharge port (29) and theprotruding part (41 b). Therefore, the size of the protruding part (41b) is made smaller than that of the discharge port (29). By so doing,the above-described smallest sectional area S1 becomes large.

Other Embodiments

The above-described embodiment of the present invention may be modifiedas described below.

The above-described embodiment is directed to the rotary compressor (1)including the piston. However, the present invention may be applied toswing piston compressors and scroll compressors. That is, the presentinvention may be applicable to any compressor as long as a so-calledpoppet valve (41) is provided at the discharge port (29) of thecompression chamber (25 b) as a working chamber.

In the above-described embodiment, the discharge port (29) is tapered.However, the discharge port (29) of the present invention may becylindrical.

Further, in the above-described embodiment, the seat (22 b) for the reedvalve (41) is provided at the outer periphery of the outlet (29 b) ofthe discharge port (29). However, the seat may be formed at the innersurface of the discharge port (29) such that it contacts the protrudingpart (41) to seal the discharge port (29).

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful as a compressor forcompressing various kinds of fluid.

1. A compressor comprising: a compressor mechanism configured tocompress fluid, the compressor mechanism including a discharge port; anda reed valve coupled to the compressor mechanism to open and close thedischarge port of the compressor mechanism, the read valve including aflat part and a protruding part formed at a distal end of the flat partto come in and out of the discharge port, the shape of the dischargeport and the shape of the reed valve being dimensioned to satisfyS2≧S1≧S0, wherein where S0 is an opening area of an inlet of thedischarge port, S1 is a smallest cross sectional area of a flow passageformed between the protruding part and the discharge port when the reedvalve is lifted to a maximum level, and S2 is a smallest cross sectionalarea of a flow passage formed between the flat part and an outerperiphery of an outlet of the discharge port when the reed valve islifted to the maximum level.
 2. The compressor of claim 1, wherein thedischarge port is tapered from the outlet to the inlet.
 3. Thecompressor of claim 1, wherein a seat is formed at the outer peripheryof the outlet of the discharge port such that the seat contacts the flatpart.
 4. The compressor of claim 2, wherein a seat is formed at theouter periphery of the outlet of the discharge port such that the seatcontacts the flat part.